The present invention relates generally to aquariums and, more particularly, to aquariums having new and improved filtration systems.
Generally, there are three types of filtration required for aquariums: mechanical, biological and chemical. Mechanical filtration capture particles such as uneaten food, bits of plants, fishes waste, etc., from the water. Biological filtration provides for the growth of a colony of beneficial bacteria that will eliminate harmful toxins in the water. Chemical filtration uses a chemical agent, such as activated carbon, to remove compounds that cause odors, discoloration of the water and certain chemical contaminants.
A number of different type filters are employed to provide the requisite filtering, such as corner filters, under gravel filters, power filters, cannister filters and wet/dry filters.
Corner filters typically comprise clear plastic boxes which sit inside the tank. An air pump bubbles air through an air lift tube, which forces water through carbon and filter floss or other media mechanically and chemically filtering the water. Colonies of beneficial bacteria build up on the media, providing excellent biological filtration. Corner filters, however, are unaesthetic, take up space in the tank, and require more frequent maintenance than other filters. Additionally, the required maintenance also removes the beneficial bacteria.
Under gravel filters work by slowly passing water through a substrate of gravel, which sits on top of a perforated base plate. The water can be pumped with an air lift, with bubbles of air lifting the water in a vertical tube attached to the filter base plate. Increased water flow can be achieved with submersible pumps, called power heads, attached to the lift tubes.
Under gravel filters make good biological filters and will foster large colonies of beneficial bacteria which neutralize toxic ammonia. They also are good at catching all debris in the water. Unfortunately, the filter quickly clogs up as all the uneaten food and other pollutants and particles choke off areas of the substrate. As greater and greater areas of the substrate choke, it results in destruction of the beneficial bacteria which decay and now add a bio load to the system. At a certain point, the remaining beneficial bacteria are overrun, resulting in a tank which is no longer able to maintain the viability of its inhabitants (a “dead tank”) which must be cleaned and reinitialized. To avoid this, it is necessary to frequently clean the substrate. Typically, this is done by regular vacuuming of the substrate. Unfortunately, the cleaning process results in removal of the beneficial bacteria colonies. Another problem might occur if an under gravel filter is used with a submersible pump. In this case, there is a safety risk from electric shock when work is done in the aquarium without first shutting down the electricity to the pump.
Another common type of filter is the power filter. There are many styles of power filters, but the most common hangs on the back of the tank. A siphon tube pulls water from the tank into the filter box and passes the water though a mechanical filter (typically a porous foam sponge). The sponge doubles as a biological filter. An internal pump then returns the filtered water into the aquarium.
The foam sponge can be easily inspected for clogging or removed for cleaning, but must be cleaned regularly to remove the solid wastes before they decompose and dissolve back into the water. Cleaning must be done in such a way, however, that the bacteria colony in the sponge is not substantially destroyed through the use of detergents or tap water with chlorine. Even if done properly, however, beneficial bacteria get removed with the debris
Canister filters have some similarities with the “hang on tank” style of power filters, but are designed to provide more powerful filtration. Typically, the water is pumped, at moderate pressure through a filter material, such as glass wool, or a micron filter cartridge. Canister filters are especially useful in aquariums which generate a lot of waste. For these filters to be effective they must be frequently cleaned, to avoid the decomposition of waste in the water stream. These filters usually sit on the floor below the tank, but also can hang on the tank, and in some designs, even sit inside the tank, in which case they are called a “submersible filter”. As discussed above, in this latter case there is a problem of electrical shock when the aquarium is serviced without first shutting down the electricity to the filter pump.
Wet/dry filters, also known as trickle filters, work on the principle that colonies of bacteria grow best in the presence of well-oxygenated water. By “trickling” water over unsubmerged media, wet/dry filters provide a very large air/water surface area. Many things can be used for the media, with the best providing great amounts of surface area, while at the same time having large openings to reduce the tendency to clog and ensure efficient gas exchange. Generally, the problem of clogging of the media is reduced by pre-filtering the water with an efficient mechanical filter.
Although all of the foregoing filters can work effectively, they do have some common drawbacks. First, they require mechanical filters. Secondly, they require frequent maintenance which disturbs the natural balance of the tank. Additionally, those prior systems which employ submersible pumps present electrical hazards and are relatively noisy. Sounds are magnified underwater and are a terrible source of stress for fish.
Further, although all existing systems are partially successful in keeping most problems temporarily in check, they do not address one of the major problems which is maintenance of the substrate. As a result, the substrate must still be vacuumed regularly to remove sediment and a substantial amount of water replaced to keep the tank viable. Even if this is done, however, the balance in the tank is never stable and varies between clean and sterile to dirty and toxic.